1. Field of the Invention
The present invention relates to a magnetoresistive effect element, and is used in, e.g., a magnetic memory having a memory cell including a tunneling magnetoresistive effect element.
2. Description of the Related Art
An application to a magnetic memory (MRAM: Magnetoresistive Random Access Memory) using a tunneling magnetoresistance (TMR) effect element (or a magnetic tunnel junction (MTJ) element) having a sandwiched structure of a ferromagnetic material/insulator/ferromagnetic material as a memory element has been proposed (see, e.g., Jpn. Pat. Appln. KOKAI Publication No. 2002-353418). In this application, spins in one ferromagnetic material layer are fixed (or made invariable) (a fixed layer or pinned layer), and those in the other ferromagnetic material layer are controlled (or made variable) (a free layer or recording layer), thereby changing the resistance between these ferromagnetic material layers in the sandwiched structure. The sandwiched structure is thus used as a memory.
In the magnetic memory (MRAM), the signal ratio of a write current to a read current is low, so the write operation and read operation are the same. When reading out data, therefore, a write error occurs because data is written by the read current owing to read disturb. To solve this problem, the variations in read current and write current must be controlled to a few %. To reduce the variations in read current and write current, it is necessary to reduce the variation in magnetization direction in the fixed layer of the magnetoresistive effect element.